The Houthi blockade

AI Summary

In July 2026, the Houthis imposed a naval blockade on Saudi Arabia, targeting Saudi-linked shipping and commercial vessels. This has led to a major decline in maritime traffic through Bab al-Mandeb and tensions about the legal status of the blockade amidst international armed conflict distinctions involving Yemen, Saudi Arabia, and Israel.

IN July 2026, the Houthis declared a naval blockade against Saudi Arabia, targeting Saudi-linked shipping, and warning commercial vessels of any nationality against calling at Saudi ports. Vessels deemed to breach the blockade faced attack wherever they entered the Houthis’ operational reach. Attacks on Saudi tankers and energy infrastructure were followed by traffic through Bab al-Mandeb falling to its lowest level in months. By September, Houthi forces had seized strategic islands around Bab al-Mandeb and gained control of Yemen’s Red Sea coast, increasing their capacity to threaten, disrupt and potentially control maritime traffic through the strait. The conventional legal position is that naval blockade is a belligerent right associated with international armed conflict (IAC), mainly because it permits interference with neutral commercial shipping. As per this view, a non-state armed group engaged solely in a non-international armed conflict does not ordinarily have the authority to impose a blockade that is binding on neutral vessels. However, customary international law does not conclusively foreclose blockade in a sufficiently intense NIAC, particularly where an organised armed group exercises extensive territorial and governmental control and can enforce maritime restrictions. This question is particularly significant in Yemen, where there is a strong argument that the Houthis function as a de facto governmental authority rather than merely an insurgent movement. They have long controlled Sana’a, govern territory containing a substantial population, and have expanded along the Red Sea coast and around Bab al-Mandeb. Crucially, under the ICRC approach, effective governmental control, rather than global recognition alone, is central to determining de facto governmental authority. If the Houthis are treated as exercising Yemen’s governmental authority, their external hostilities may be characterised as those of Yemen itself, strengthening the argument that the relevant conflicts are international and that traditional belligerent rights, including blockade, are potentially available. Even if this characterisation is rejected, other factors point towards possible internationalisation. Saudi Arabia is directly engaged alongside the internationally recognised Yemeni authorities against the Houthis, while the latter have repeatedly attacked Saudi territory. Saudi intervention by invitation does not, by itself, transform the underlying conflict into an IAC, but it adds an international dimension. Israel provides a separate route: it has used force on Yemeni territory in response to Houthi attacks, and under the ICRC’s view, the unconsented use of force by one state against another state’s territory may itself create an IAC between them, even where the immediate target is a non-state armed group. Israeli strikes on Houthi-held territory could therefore support a parallel Israel-Yemen IAC. Do the Houthis, as a non-state armed group, have the legal authority to enforce a naval blockade? Iranian involvement provides another possible route to internationalisation. Arms, financing and political support alone are insufficient. Under the International Criminal Tribunal for the former Yugoslavia’s “overall control” test in Tadić, however, the threshold may be met where a state, beyond financing, training or equipping an organised armed group, also participates in planning its military activities; specific instructions for each operation are unnecessary. The ICJ’s stricter “effective control” test, relevant to attribution of particular conduct, requires proof that the state directed or controlled the specific operation in question. Accordingly, if the conflict is international, traditional blockade law is more readily applicable; if the Houthis remain solely a non-state party to an NIAC, their authority to impose blockade obligations on neutral shipping remains controversial. In either case, a declaration alone is insufficient: a blockade must satisfy the requirements of effectiveness, notification, impartiality and applicable humanitarian limitations. Regardless of classification, the Houthis are bound by applicable international humanitarian law. In an NIAC, Common Article 3 of the Geneva Conventions and applicable customary IHL apply; in an IAC, the Geneva Conventions apply in full, together with customary IHL. In either case, rules governing distinction, military goals, proportionality and precautions constrain the conduct of hostilities. The law of naval blockade is further governed by the law of armed conflict at sea and customary international law, as elaborated in the San Remo Manual. Under paragraphs 93-104, a blockade must be declared and notified to belligerents and neutral states; specify its commencement, duration, location and extent; allow neutral vessels an appropriate period to depart; be effective and impartially applied; and comply with humanitarian restrictions, including those concerning esse